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KentuckyFC writes to mention that new data from the orbiting observatory PAMELA may shed some additional light on the question of dark matter. Still only a preliminary announcement, the new findings apparently support the "Minimal Dark Matter" model, in which a particle called a "Wino" is responsible.

You see... If anything proves that Twitter has hacked the moderation system, it's this.Something very strange happens to Slashdot... We better fight it before it's too late, and Slashdot becomes a cross breed of 4chan and the Youtube comment section.

Yet, upon further examination by the Arecibo radio telescope, an excerpt of audio in a continous loop is being transmitted from the area. It contains the following messsage:
"What's the word? Thunderbird!"

Yet, upon further examination by the Arecibo radio telescope, an excerpt of audio in a continous loop is being transmitted from the area. It contains the following messsage:
"What's the word? Thunderbird!"

Humans have sent back the response, "How's it sold?". We all anxiously await the answer to one of life's mysteries.

I very often see articles saying the Dark Matter is found. This has been going on for years already. Articles titled "Dark Matter Found". But later another article pops up again saying "Dark Matter Found" and it'll have a totally different explanation, be it some new particle type, some mathematical construct, something that says that in fact it doesn't exist and it's another effect, or again another particle type.
So basically, they just don't know?

more positrons than can be explained by known physics and that this excess exactly matches what dark matter particles would produce if they were annihilating each other at the center of the galaxy.

Yep, it's very much as you describe. Many of these models push the boundary of what can be called 'theory' in scientific terms, but they are the best we have so far. I think what's getting people excited is that the observations mentioned in TFA are predicted by a dark matter theory.

I very often see articles saying the Dark Matter is found. This has been going on for years already. Articles titled "Dark Matter Found". But later another article pops up again saying "Dark Matter Found"...
So basically, they just don't know?

No, it shows that bloggers and reporters (and slashdot editors) need to sensationalize preliminary results or possible explanations to get readers.

Galactic clusters do not appear to have enough mass to account for their speeds. Similarly, Galactic rotation curves flatten out as if galaxies were shaped spherical balls, even though we can see they are discs. The very first thing that astronomers reached for to explain these phenomena was as yet unseen, or "dark" matter.

Personally (I am a lay person astronomically), I think Dark Matter raises more questions than it answers. While I acknowledge the effort, time and rigor that many astrophysicists have put into studying these phenomena, I still feel that dark matter, a substance which is invisible, intangible, and undetectable expect through its gravitational effects is too far of a step for physics to take without more evidence. I feel as a theory, dark matter is only a stepping stone on the way to a better explanation for what we are observing.

I think the theory has fed off its own inertia. While "Dark Matter" was proposed in the 1930's by Zwicky, he meant it only in the classical sense, i.e. dust, dim stars, etc. The dark matter we hear about today seems to be a product of the 1970s, and is I think a result of the influx of particle physicists into the discipline of cosmology beginning in that period. The particle physics community has had a history of success using assumptions and models that are counterintuitive and often bizarre. The idea we hear most of today of more "exotic" and inscrutable dark matter stems I think from this camp.

The proposal of alternative theories has also ironically lead to wider acceptance of dark matter. By proposing alternatives, sides and factions were created, as will always happen among groups of people when topics are in dispute. When a theory like MOND fails in a particular case, this has the effect of strengthening confidence in the Dark Matter model, even though it should do nothing of the sort. Only sold predictions which emerge from a model should inspire confidence in it, and despite all the fanfare, we have no way of measuring dark matter, even indirectly. The distribution of the dark matter "halos" or spheres, is still an unknown, and some galaxies do not appear to need dark matter at all.

All that said, Feynman's rebuttal still applies. The laws of nature do not have to be philosophically pleasing to us. The universe does not exist for our mental gratification. It can be as strange as it wants to be, and if we don't like it, that's out tough luck. So if dark matter makes predictions, and they fit the data we see, then it is a good model no matter how strange its premises.

All that said, at this time I would bet on a better theory emerging at some later date. Exotic matter, while it may work in subatomic circles, will not I think stand up to scrutiny in the macroscopic domain.

Personally (I am a lay person astronomically), I think Dark Matter raises more questions than it answers. While I acknowledge the effort, time and rigor that many astrophysicists have put into studying these phenomena, I still feel that dark matter, a substance which is invisible, intangible, and undetectable expect through its gravitational effects is too far of a step for physics to take without more evidence. I feel as a theory, dark matter is only a stepping stone on the way to a better explanation for what we are observing.

That certainly is the nightmare version of Dark Matter. However, most (if not all?) dark matter models do not in fact propose (other than gravitationally) noninteracting particles. They certainly must interact very weak with each other and ordinary matter but not per se not at all.

Dark Matter models make in fact verifiable predictions, such as annihilation products and rates (positrons in this case). They are valid science!

The very first thing that astronomers reached for to explain these phenomena was as yet unseen, or "dark" matter.

It has worked in the past, though. Remember how the observed motion of Uranus differed from the predicted motion? A hypothesis was put forward that the difference was due to the gravitational effects of a large body of dark matter. After some mathematical work, the likely location of the dark matter was deduced, someone went to a telescope and had a look - and there it was. Time to crack open the champagne and think of a name for it, how about 'Neptune'?

It has failed in the past too: the motion of Mercury also differed from what was predicted, and the hypothetical planet Vulcan was suggested as the cause. Yet after many searches, there was no sign of Vulcan. It wasn't until the general theory of relativity replaced Newtonian gravity that this was cleared up.

Whether we're about to discover another Neptune, or another general relativity, remains to be seen; the point is that the Universe is pulling something weird on us, and that's interesting.

There's a difference: aside from a force of gravity that just has whatever local strength it feels like, it doesn't appear that you can modify the force of gravity to account for all the effects we see. Dark matter, however, can explain all those observations.

In order for a modified gravity theory to work it also requires a certain amount of dark matter.

There's a big distinction between the general dark matter theory and particular candidates for dark matter. The general picture is supported by numerous different lines of evidence: not just galactic rotation, but by gravitational lensing, the microwave background, structure formation, etc. It has been much more successful than any modified gravity theory thus far. It's a good model thus far, and we'll drop it if other observations come along.

There are literally hundreds of specific theories of dark matter's composition, however, and those are individually on shakier ground. These are mostly particle physics models emerging from the 1980s. There are an infinitude of papers and preprint suggesting this or that candidate and what signatures it could generate. They do all make predictions, however, and our observations are getting good enough to test many of them. Between astrophysics and particle accelerators we have a real chance of figuring this out (and the PAMELA observation seems unusually interesting!)... but there are a lot of overblown claims in the media in the meantime.

It's not that it's impossible that there are particles which don't interact with EM. The problem is that the only evidence offered for dark matter is 'we can't see this stuff so it must be some new exotic particle.'

I've yet to see evidence that Zwicky was wrong when he suggested that there were objects made of normal stuff that were just too dim for us to see. It may not be as sexy an explanation but until it's demonstrated not to fit the facts, why has it been discarded?

There is definitely such evidence - it comes from Big Bang Nucleosynthesis. The idea is that the light elements (deuterium, helium, lithium) were produced when the early universe had temperatures conducive to fusion. This phase only lasted a few minutes, and the abundance of the light elements today depends sensitively on the conditions during this period. The abundance of deuterium tells us pretty clearly that the total mass of matter (which affected the temperature profile during nucleosynthesis) was much greater than the total mass of ordinary matter (which participated in the fusion process). Similar evidence comes from the cosmic microwave background.

Astrophysicists did not initially want to believe that the missing matter was exotic, but there's some extremely compelling evidence!

The very first thing that astronomers reached for to explain these phenomena was as yet unseen, or "dark" matter. Personally... I think Dark Matter raises more questions than it answers.

The reason they reached for Dark Matter is that it is the simplest explanation. It is very easy to imagine that there is more mass there than you can see. It is a lot harder to start adding new forces or modifying existing ones. It certainly raises new questions but that does not exclude it from being the simplest solution.

dark matter, a substance which is invisible, intangible, and undetectable expect through its gravitational effects is too far of a step for physics to take without more evidence.

Er...what do you think we are doing? We are looking for that evidence. You are contradicting yourself here: we think DM is the best explanation to date so we are now looking for evidence to confirm it. If we had "taken the step" and truly accepted Dark Matter as the truth why would we bother searching for evidence of it? Also there are very good reasons to think that it interacts through the weak force as well as gravity - although it is not a requirement.

The particle physics community has had a history of success using assumptions and models that are counterintuitive and often bizarre.

We have? What part of particle physics is counter-intuitive? I think you are getting confused between Quantum Mechanics (which is very counter-intuitive) and particle physics. The Standard Model of particle physics is generally very simple, straight forward and easy to understand at a basic conceptual level - it is even sometimes taught at secondary school level.

When a theory like MOND fails in a particular case, this has the effect of strengthening confidence in the Dark Matter model, even though it should do nothing of the sort.

Why is this wrong? If, as is the current case, all alternative theories to DM have series flaws, then you end up with only one candidate theory to test so naturally there will be more work being done on it. I think you are confusing belief with knowledge. A lot of us believe that DM is likely to be correct but none of us know it to be correct. As the best theory to date there is a lot of interest in proving it correct so we look for data to do that.

we have no way of measuring dark matter, even indirectly.

Wrong - there are ways to measure it directly but they depend on the type of dark matter. We can produce it directly in the LHC, we can search for its interactions with nuclei in low background locations deep underground like SNOlab. These experiments have already put limits on what the Dark Matter could be. So far they have not seen anything but that does not preclude them from seeing it.

Exotic matter, while it may work in subatomic circles, will not I think stand up to scrutiny in the macroscopic domain.

...and yet neutrinos, which are now known to have a mass, are an example of exotic matter and standup to scrutiny very well indeed.

You're correct that a lot of the explanations are exotic and inscrutable, that's because if it was something ordinary we wouldn't have the problem in the first place. It's like we have a giant equation and it doesn't balance, either we're missing a term or one of our terms is very wrong. Either way it's going to be something new and strange because the old and ordinary clearly isn't the answer.

While I acknowledge the effort, time and rigor that many astrophysicists have put into studying these phenomena, I still feel that dark matter, a substance which is invisible, intangible, and undetectable expect through its gravitational effects is too far of a step for physics to take without more evidence.

I have to ask - why ? From what we know, there are four forces (strong, weak, electromagnetic, gravitation) that we can use to detect particles. We already know a lot of particles that cannot be detec

No. Big bang nucleosynthesis tells us that baryonic matter (that is, made up of neutrons and protons, basically) only makes up a small percentage of the total matter mass of the universe. That is, there is an awful lot of matter out there which is not made of protons and neutrons; it is exotic.

It is worth pointing out that we have not located all of the baryonic matter out there yet, and much of that may well be rogue planets, brown dwarfs (black dwarfs haven't yet had time to form), etc. These are com

I ask this - why would there be dark matter at the core of the galaxy? Doesn't dark matter repel normal matter?

No - Dark Matter is, gravitationally, exactly the same as normal matter. You are thinking of Dark Energy which is not matter. It has a positive energy but behaves as something which is gravitationally repulsive...as far as I am aware there is not even a good theory as to what this stuff is let alone experimental evidence of its nature.

I very often see articles saying the Dark Matter is found. This has been going on for years already. Articles titled "Dark Matter Found". But later another article pops up again saying "Dark Matter Found" and it'll have a totally different explanation

I don't think you're paying very close attention to what's being reported. Dark matter research isn't continually contradicting itself with new explanations every week.

In the late 1990s, some dark matter was found in the form of MACHOs (basically, brown dwarves and things), but it wasn't enough to explain what all the dark matter was. Since then, more attention has focused on WIMPs (new kinds of particles). Observational studies have continued which have been able to exclude some kinds of WIMPs (e.g., it

Well, there are efforts to spackle together a theory that combines MOND and neutrinos as an alternative to WIMPs. It's comparatively unsuccessful at the moment, but one can never be quite sure what's going to come flying out of left field.

There are possibly many different aspects to dark matter. There only common factor is we don't know how to detect them yet. For an example take the atom. The name means "indivisible", or the smallest unit, but guess what, we found out that that premise was false.If they keep claiming to find new particles, then tally the mass there should gradually be a reduction in the amount of matter unaccounted for. Assuming of course that the "missing" mass is necessary, and there isn't another reason for the observed

I was always of the impression that even if you shed light on dark matter you still wouldn't see it, and if you did , we already would. But I commend the initiative, and wish the best of luck to any and all who attempt to shedding some light on the matter of dark, shed some dark on the matter of light mass, shed some mass in order to become become light, or even just light some dark sheds.

I've always heard the opposite... That dark matter isnt any different at all from normal matter, it's just that we don't know where it is. We know it's out there someplace because the mathmatical models rely on there being "extra" mass out there still work when compared to reality.

I'm afraid the OP was correct. You can't shed light on dark matter because the dark will suck all the light, just like the sun sucks dark so hard that the friction of the dark moving to the sun causes it to become very hot. The flow of dark towards the sun interrupted by the earth causes the side of the earth away from the sun to accumulate dark, thus causing Night. As the earth rotates the dark caught on the night side can then be pulled off, this causing the absence of dark known as Day.

What we call light bulbs are truly dark suckers as well. That is why light bulbs are hot, just like the sun. When a light bulb is full of dark and won't suck dark any more, it cools off. If you look in old light bulbs you can even seen the accumulation of dark.

And when he said shed some dark on the matter of light mass, shed some mass in order to become become light I think he was referring to the fact that dark is heavier than water (in the oceans, the deeper you go, the darker it gets).

To clarify slightly, there are two kinds of dark matter. There is "dark ordinary matter", which is just gas and dust that we can't find. We've now found most of that. The vast majority of the missing mass, however, is NOT ordinary matter. This is the mysterious part.

That kind of reminds me of the old Ptolemeian model of the planets. Planets were assumed to move in perfect circles. If that didn't fit, they added little circles onto the larger circles that the planets moved by.

And if that doesn't explain the whole thing... "well, then there must be some circles that we don't know about yet. The rest of it still compares to reality."

Then Kepler came along and showed that they move in ellipses. Maybe we are just waiting for the next Kepler to solve this one.

Can someone astrophysically informed explain how the charged wino [wikipedia.org] can be a dark matter candidate? Photons would interact with it through its charge, now? Or are they talking about the zino (same link)?

Back when I was in particle physics, we would pronounce "wino" to rhyme with neutrino, but we would still snicker about it.

The charged wino would not be a reasonable dark matter candidate for just the reason you give: it would interact with light and we would have detected it by now. The dark matter candidate should be uncharged and thus a partner of an uncharged particle, e.g. a zino or photino.

There's a terminology issue, however (here comes the boring part). The electromagnetic (photon) and weak forces (W+/- and Z) are understood to be aspects of a unified electroweak force. In electroweak theory its more convenient to talk of 3 W fields (+/- and neutral) and one neutral B field. The photon is a mixture of the neutral W and B, the Z is another such mixture.

The most common dark matter candidate (the lightest neutralino) is a mixture of the supersymmetric partners of these particles: the neutral bino and neutral wino (and two neutral higgsinos). We could just as well say that we're mixing the photino and zino (and two neutral higgsinos), but bino and wino are more common terminology.

The paper is speaking about a dark matter candidate which is primarily the neutral wino, with a little admixture of the other states. Note that this doesn't mean the dark matter is composed of multiple different particles, just that the one particle it is composed of is "in-between" these labels.

Don't be fooled by this guy! He's not really talking about physics. I saw some 'particle physics' equations left on a whiteboard the other day. A postgrad told me it was important physics and I wouldn't understand, but I'm sure there's some kind of hidden message:

The actual arxiv paper [arxiv.org] contains no references to the term 'wino'. And they clearly states that their candidate is neutral. I've seen mentions of a 'wino-like neutralino' as a candidate for dark matter in different papers, but I'm unsure of what exactly makes it 'wino-like'. It is certainly not charge.

Wino.Well the very fact that we're talking about Wino means it is observable, even if only by the absence of something else.

Wine.
From winehq [winehq.org], "Wine is a translation layer (a program loader) capable of running Windows applications on Linux and other POSIX compatible operating systems."
From dictionary.com:
emulator. 1. to try to equal or excel; imitate with effort to equal or surpass
3. Computers. a. to imitate (a particular computer system) by using a software system, often including a microprogram or a

The linked article is a summary of a paper that has an analysis of data not written by the original PAMELA team who collected the data. The PAMELA team have not yet published their data or findings, although apparently have presented them at a conference in Stockholm.

The summary quotes the paper thusly: "The preliminary data points for positron and antiproton fluxes plotted in our figures have been extracted from a photo of the slides taken during the talk, and can thereby slightly differ from the data that the PAMELA collaboration will officially publish."

I am not familiar with the conference in Stockholm that the PAMELA data were originally presented at, but at every large conference I have attended, it is official policy that no photographs are allowed. Taking unpublished data without permission of the authors is theft, pure and simple. Submitting a paper on that data before the original authors do is unethical.

Certainly, such proclamations are made with scant and incomplete information (it could be that Cirelli and Strumia, the non-PAMELA authors, did indeed get permission from the PAMELA team, and everything is kosher), and I hope that either members of the PAMELA team or authors of the new paper might read Slashdot to explain what's going on.

There are other definitions of what constitute theft than what qualifies as such in the view of a US court, you know. If circumstances are as they superficially appear, what those people did, morally and ethically, is theft pure and simple, and it matters not a whit whether they could be arrested for it.

Theft, in common parlance, involves depriving someone of rightful possession of property. No one was deprived of possession of property here, and so there was no theft. In fact, it appears that there wasn't even any copyright infringement.

What they did was unethical. Why can't you just call it that? Why the need to attach a dramatic and inappropriate label such as "theft"?

Again, assuming that matters are as stated, because they were deprived of the tangible and intangible benefits of being first to formally publish their own work, and because any opprobrium attaching to misuse of their data will inevitably affect them to some degree, it can be assumed by reasonable people that they're likely to suffer some damage from the theft.

If you take the trouble to read the short OED entry on theft, offered here for your convenience, you'll note that at least two of the definitions

Thief! With your deft counter-argument you've clearly deprived the GP of his sense of self-assuredness. Not only that, but you've raped his self-confidence with the vile intrusion of your logic into his mind.

...Or perhaps we could abandon the colorful metaphor and agree that unless you go into a person's lab and abscond with his lab notebook you are not, in fact, committing theft. I've no doubt that one can use metaphor and idiom to stretch the meaning of any term to near uselessness, but if we wish to

Blame those nasty, evil languagistas at the grand old OED. A definition stated clearly (and stated early in the entry) in Oxford can scarcely be considered metaphor or idiom. It is, if I may descend to synecdoche, the very soul of the word.

I am not familiar with the conference in Stockholm that the PAMELA data were originally presented at, but at every large conference I have attended, it is official policy that no photographs are allowed. Taking unpublished data without permission of the authors is theft, pure and simple. Submitting a paper on that data before the original authors do is unethical.

Not everyone thinks that way. Some of us think that publicly presented information is fair game. And just because I have not spent the necessary ef

Some of us think that publicly presented information is fair game. And just because I have not spent the necessary effort to develop exact memory does not mean I cannot augment it with a device.

I fear you are mistaken, in a strict legal sense. Whether you are allowed to take a recording (audio or visual) of a presentation is up to the organizers of the conference, not you. Smaller conferences generally allow it by default, and larger conferences generally do not. Generally. I have organized two smaller

I fear you are mistaken, in a strict legal sense. Whether you are allowed to take a recording (audio or visual) of a presentation is up to the organizers of the conference, not you. Smaller conferences generally allow it by default, and larger conferences generally do not. Generally. I have organized two smaller conferences and have paid specific attention to this issue.

I hope you made the right choice:) Personally, I would consider the conference where one cannot take notes several notches away from scien

"This is an unfortunate corruption of the scientific method by the current grant system of running science."

Bullshit, what's the point of doing the "95% persperation" part of obtaining funding and collecting the data if you are going to allow every other 'genius' to beat you to the 5% inspiration part and get all the glory/future funding?

"The original idea was that a claim is judged by its merit."

The presentation was not supposed to be convincing anyone of anything, it was to enlighten others in th

It's unlikely. We're pretty sure we have a decent idea of the amount of normal matter created in the big bang and it agrees with our estimates of the amount of matter we can see pretty well. For various reasons dark matter is unlikely to be just non-radiating normal matter. Some of these reasons are direct observations: galaxies colliding and the normal matter going one way (including the non-luminous cold gas, which in the collision gets hot, starts radiating, and forms stars), and the dark matter con